True Blue 12"x12"x1" Fiberglass MERV Rating 2 30-Day Filter. It effectively captures pollen and dust/lint, reducing dust and dirt buildup in air ducts, air conditioners, and furnaces. Made from heavy chipboard in a one-piece design, this filter features continuous filament spun glass media that adheres directly to the frame, eliminating the need for a retainer. UL Classified.